Radio Control Helecopter.

This had been sat negelected for a long time (over a year !)! Cheap radio control helecopters have come on a bit since this model was given to me for repair (and forgotton about !) but I decided to get it done anyway.

Only one of its twin rotors would spin.

The two motors were wired to a dual n channel mosfet package, only one motor spinning tended to indicate one dead mosfet ! It was a FDS8926A (8 pin package just next the red wire closest to the bottom of the pic) , a replacement chip was sourced for <£1 and fitted, the original chip was definitely dead as it had a hole burnt in it ! Observational repair is so useful, no matter how complex a system is, a very very good look can lead to a fix without in depth knowledge of a circuit.

The motor still would not spin ! I swapped the motor wiring over, it drove the other motor just fine so I stripped the non functioning motor.

It was tiny (fortunately not as tiny as the rear rotor !). Inspection showed that one of the tiny leafs of metal that act as brushes to the commutator had vapourised, probably an over current situation took out the brush and mosfet.

I thought this was dead and buried but I managed to re form the contact by bending it differently, the motor now worked and the helecopter was airbourne once again !

Nintendo DS Lite game cartridge slot.

Another DS Lite already ! (another pink one, in fact two).

This time the cartridge slot contacts had been damaged ! in fact two machines were damaged but I only had one donor connector this time.

The pic shows the connector off the board (exposing the usually hidden ARM CPU), I used a huge iron tip and solder braid to clear the tabs, then levered them clear with a scalpel. Then I removed the PCB connectors by flooding with low temp solder (google youtube chipquick for details on the method, or see my first blog post).

I need to order another off eBay, only £1.50 from HK or £4 from UK.

Nintendo DS Lite & DSI shoulder buttons

A couple of Nintendo DS's to look at, these are so popular, everybody seems to have several. Ive got a huge bag of bits from previous repairs. Re shelled ones, liquid damaged ones, damaged screens and digitizers.

Today was faulty shoulder buttons, one on a Lite one DSi. I hadt had a DSi appart before, it wasnt obvious from google or ebay but the switch is the same for both machines. I had a donar board for switches but thery are pretty cheap on ebay.

Here is the DS Lite with the switch about to go on.

Both the faulty switches clicked fine but were intermittent with their response, new switches fitted everything worked fine.

Yupiteru VT125 ii Scanner

This needed a general overhall, the DC jack had disintergrated and it wouldnt power off batteries.

The battery box was heavily cooroded from leaky batteries, so that got a good clean up using a brass wire brush.

Inside there were three poor connections, one was held on with blu tack (well a white tack) ! (I like blue tack, see previous post) but as a substitute for soldering it isnt great :-) My university lecturer one found a student using araldite to make up a DB25 ! those full time students ehh :-)

The other two poor connections were to the two battery trayposts, the wires were just wrapped round ! See pic below? I can believe this was original, so that wiring was replaced and soldered.

You can see the disintegrated DC jack, this has been removed and a replacement part sourced, the only one I can find to fit the PCB layout is 1.3mm pin, seems abit small for this era, I have asked the owner if he has the PSU so I can check for size, (web search didn't come good on this).

Works a treat off batteries now, just waiting for the PCB jack.

3 Network £10 sim in iPhone 4

Nothing of great note but Google didnt come good for me on this and the 3 website certainly didnt.

Its seems very common that becasue the iPhone 4 uses a microsim that carriers create special tarrifs for them, you might call it an iPhone tax in some cases ! on '3' their lowest price 30 day sim only deal isnt available on a micro sim so the obvious solution is to cut the regular sim to fit, Im just posting to confirm that this works fine, there are no special settings relating to the microsim or iPhone 4, and 3 dont flag it up.

There is no visual voice mail on any uk provider other than O2 which is a pity but 3's sim only is £5 less than 02's equivelant on 30 day contract (need to go 12 month on O2 for equivelant).

Ive cut a number of sims now for the iPhone and the iPad, one tip is that if you remove too much material, dont panic !, you can use blu tack to fill the gap and hold the sim in place in the carrier !

HTC HD2 part 2

My friend took his HD2 back to get the screen and digitizer replaced for the second time (see earlier post).

He got it back, only now volume buttons on the side dont work !

Opened it up and found out the reason, not good (look just left of the FCC logo on the back sticker)

When they put the phone back together they routed the cable to the volume PCB incorrectly and it got snapped off. Initially I didnt think this could be too bad but its not good news. The volume pcb is hard wired to the cable, the cable in turn travels under the phone serial number sticker where it becoms part of a huge ribbon cable that seems to be referred to as the flex assembly, it also contains the camera module connector amongst other things, its not cheap,£42 and a bit fiddly to fit, but what isnt on this phone !

He refuses to take it back to the shop to be butchered again so a repair is currently undecided, phone functions ok and the volume can be adjusted from the touch screen.

We will see if he goes for the new flex assembly. Heres a picture of it. Volume buttons on the right. Interestingly there is one for sale on eBay for just £5...with the volume controlls snapped off, watch out if you have to strip a HD2, obviously not a one off!

HTC HD2

A friend had his screen and digitzer replaced after dropping it. He paid £100, didnt seem to bad, the lowest I have seen the pair for currently on eBay is about £70.

However on return the GPS didnt work and there was a blob in the middle of the screen.

I opened it up following this video, not quite as easy as they made it look but a big help. Plastic prising tool was a must, I got a good selection of these off ebay for £1 a set delivered.



http://www.youtube.com/watch?v=cL-jnUKufC4&feature=player_embedded

It turned out to be the antenna connector for the GPS had come off (not at the camera end, a little harder to get at where it was off), refitted and bingo, we were back in action. The connector is very fiddly and takes a lot of pressure to fit, not a lot for it to come off !

The blob on the screen I suspect is liquid from when laying the digitizer over the screen, he decided to take it back for this issue. I was tempted to gently heat and squegee it off but better to go back to the shop realy. The main thing was to check the phone hadnt been damaged inside and be prepared for the shops response it it had ! thankfully it hadnt.

Ive had a few HTC devices apart in the past, overall impressed with the quality of construction. (wish I could say the same of HP DV series laptops !!, maybe I will discuss if I get another nvidia reflow to do !)